We are entering an exciting era in pediatric rheumatology. New treatment approaches are improving the lives of children with juvenile idiopathic arthritis (JIA) to such a degree that it's now rare to see wheelchairs or crutches in our waiting rooms. Even splints, commonly used in the past to treat joint contractures, are seldom seen on our patients. Despite our progress, remission in JIA is rare. Recent work by our collaborator, Dr. Carol Wallace, has shown that only 5% of children with the polyarticular JIA (the most severe form of this disease) are in remission 5 years after diagnosis. Part of our problem in achieving remission is that, at the biological level, we don't really understand what remission is. It's a classic case of the difficulty of getting somewhere when you don't really know where you're trying to get. This grant application is about learning where we are trying to get. In this application, we aim to achieve a better understanding of what remission is using microarray-based biomarkers. Research from the Cobb (acute inflammation) and Jarvis (chronic inflammation) laboratories has demonstrated the feasibility of using genome-wide expression profiling can be used to define disease states (e.g., infected vs. not infected; in remission or not in remission). Furthermore, the Jarvis laboratory has demonstrated the promise of using these same technologies to predict clinical outcomes. For each group, these promising preliminary studies must be validated using larger patient populations and prospective study designs. In this application, we propose to validate peripheral blood biomarkers that already suggest that: (1) remission in juvenile arthritis can be identified at the molecular level through distinct gene expression signatures; (2) those signatures include the balance of both pro- and anti- inflammatory gene networks; and (3) the clinical course of children who reach an inactive disease state can be predicted based on molecular signatures that emerge in the peripheral blood mononuclear cells. Furthermore, we will take another step toward clinical application of this work by developing PCR-based whole blood assay to identify the most robust indicators of remission or clinical outcome. This project brings together two experienced investigators from two very different disciplines: pediatric rheumatology (Dr. Jarvis) and surgical intensive care (Dr. Cobb). Furthermore, the project brings together two computational biology groups spanning multiple disciplines, as well as other experienced pediatric rheumatology investigators. Thus, the project is highly responsive to the goals of the most recent NIH roadmap.